Catalyst assist agents using leaving group effects

ABSTRACT

Leaving group effects provide a number of advantages in processing of cellulosic or cellulose-containing textiles. In particular, the rate of reaction of agents or compounds with cellulose can be increased in two ways. First, the reactivity of derivatives of N-methylol type agents and the reactivity of derivatives of hemiformals can be increased by proper choice of leaving group. Second, the leaving group forms a material which is acidic enough to assist in the catalysis of reactions with cellulose.

United States Patent 1191 Vail 1 Nov. 13, 1973 .[22] Filed:

[ CATALYST ASSIST AGENTS USING LEAVING GROUP EFFECTS [75] Inventor: Sidney L. Vail, New Orleans, La.

[73] Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.

June 29, 1972 [21] Appl. No.: 267,312

[52] US. Cl 8/186, 8/181, 8/182, 8/184, 8/186, 8/187, 8/ll5.6, 8/116, 8/120, 8/129, 117/139.4, 252/8.8, 252/429 R, 38/144 [51] Int. Cl. D06m 15/56, D06m 15/58 [58] Field of Search 8/181, 182, 184,

[56] References Cited OTHER PUBLICATIONS Vail et al., Textile Research Journal 40, 355-362 (1970).

Vail, Textile Research Journal 41, 336-344 1971 Vail, Textile Research Journal 42, 360-367 (1972). Vail et al., Textile Research Journal 42, 367-373 (1972).

Primary Examiner-George F. Lesmes Assistant Examiner-J. Cannon Attorney-R. Hoffman et al.

[57] ABSTRACT 5 Claims, No Drawings CATALYST ASSIST AGENTS USING LEAVING GROUP EFFECTS A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the treatment of cellulosic textile materials to produce textiles having improved physical and chemical properties, such as durablepress, flame resistance, weather resistance, and dimensional stability. Specifically, this invention relates to the process for treating cotton or other cellulosic fabrics with formulations which contain chemical compounds which are activated by leaving group effects thereby imparting to treated fabrics wrinkle resistance and durable-press properties. More specifically, the present invention relates primarily to the use of reactive catalyst assist agents wherein the leaving group from the catalyst agent forms a material which is acidic enough to assist in the catalysis of the reactions with cotton. In general, these catalyst assist agents are useful in acidcatalyzed processes in resin applications, textile finishing, plastics, pharmaceutical, and allied industries or as intermediates in these fields. The reactivity of N- methylol compounds and their derivatives in acidcatalyzed reactions has been explained [Textile' Research Journal 40, 355-362 (1970) and Ibid. 41, 336-344 (1971)] on the basis of stability of resonancestabilized intermediate ions and leaving group effects. This concept can be illustrated through the use of a generalized structure, R(CO)NI-ICI-I X, for the reactive material, wherein X represents the leaving group and the resonance-stabilized intermediate ion is represented as follows:

In an acid-catalyzed reaction X may be considered to combine with a proton to form I-IX whereas the intermediate ion may be considered to react with cellulose to form:

I R(CO)NIICH,O Cellulose l-Ieretofore, the textile industry has primarily been concerned with reaction systems wherein X was OH or occasionally OCI-I and the leaving group, by addition of a proton, formed water (HOH) or methanol (I-lCI-I,). In such cases the leaving group effect (where R is constant or unchanged and X=OH or OCI-I,) has only a minor influence on the relative reactivity of these reagents. Thus, the major influence on the relative reaction rates is determined primarily by electronic and steric effects produced by R if the leaving group is limited to those usual cases where X=OI-I or OCH,

On the other hand, when the leaving group forms secondary alcohols, such s cyclohexanol or isopropanol, and R is not varied, there is a noticeable increase in reactivity over the comparable reactant where X==0Hor OCH, Further, leaving groups which form organic acids, such as acetic acid, produce a noticeable increase in reactivity because of the leaving group effect.

There are a number of problems associated with this process. The interaction of intermediate ion stability and leaving group effects can result in some cases where the relative reactivities of the reactants are not predictable (See above references). Also, conversion of N-methylol compounds into esterand ether-like compounds often reduces the solubility of material in water andvthese new compounds are not suitable for normal usage wherein aqueous solutions are used in textile finishing. In addition, agents which are made highly active by use of a good leaving group may hydrolyze in the pad bath and regenerate the starting N- methylol agent or other corresponding intermediate products. Clearly, this occurrence defeats the purpose of preparing an activated agent, because it is the rapid reaction with cellulose whichis desired.

Derivatives of hemiformals or hemiacetals can function in a fashion similar to derivatives of N-methylol compounds in that the leaving group effect can both activate the molecule and also release an acid to assist in the reactions with cotton. The mechanism of these reactions are believed to be similar to those discussed previously in that reactivity is governed by intermediate ion stability and leaving group effects. Acyl derivatives of hemiacetals produce a mixed acetal of cellulose which may then react further to crosslink cellulose. For example, acyl derivatives of hemiformals may react to form a cellulose alkyl formal, i.e., Cell OCI-I OR, which reacts further under acidic conditions to form Cell OCI-I O Cell.

Recovery of a product from the leaving group must be considered in some cases. Volatile products of economic value, generally secondary alcohols or acids, are released in processing-preferably during the curing operation. Release of large quanties of these materials can obviously produce conditions dangerous to the health and safety of workers. 7

The primary object of the instant invention is to provide a type of activated reagent which can be used in textile finishing, especially durable-press, procedures as a catalyst assist agent, whereby the conventional curing catalyst is activated by release of unobjectionable quantities of acidic material from the activated agent.

These and other objects of the instant'invention are accomplished by treating the cellulosic textile with an aqueous solution containing a crosslinking agent, such as dimethyloldihydroxyethyleneurea (hereafter referred to as DMDHEU); a conventional curing catalyst, such as magnesium chloride; and a catalyst assist agent which is neutral in aqueous solution but which forms-an acid as strong or stronger than acetic acid; i.e., acids in aqueous solutions at room temperature which have a dissociation constant greater than 10, on reaction with a nucleophile such as cellulose, water, alcohol, and similar materials.

The chemical structures of the specific catalyst assist agents used in the process of this invention are shown below:

. The additionof these materials to a conventional textile treating solution has essentially no immediate effect upon the pH of the solution. However, the release of acetic acid during processing markedly reduces the pH of the system.

The .time of actual release of the acid is controlled by the treatment conditions and by the reactivity of the catalyst assist agent, and, as noted previously, the reactivity of these agents is controlled by intermediate ion stability and leaving group effects. Once release of the acid has begun, the reaction of the catalyst assist agent becomesauto-catalytic. In general, those acids which are relatively strong are produced by the better leaving groups; whereas those acids which are relatively weak are produced by leaving groups which do not activate the agent as much as do the aforementioned better leaving groups.

The volatility of the catalyst assist agent may also determine the effectiveness of the agent Methoxymethyl acetate (boiling point about 118 C) must release acetic acid relatively early in the curing process, if heating at elevated temperatures is involved, or it could be removed by distillation and might not be effective. However, acetoxymethyl methyl carbamate is less volatile and is not expected to distill from the fabric during a curing operation which requires heating.

On the other hand, it should be obvious to those skilled in the art that volatility of the catalyst assist agent would have essentially no influence upon the effectiveness of most processes wherein curing or fixation of reactants is carried out in the wet stage below the boiling point of the catalyst assist agent.

Similarly, the objectives of this invention can be met through use of a solvent system other than water. For example, isopropoxymethyl acetate has a higher boiling point than methoxymethyl acetate and would be more suitable for heat cures because of its lower volatility. However, isopropoxymethyl acetate is not soluble in water (less than 2 percent by weight) and therefore is preferably used in a nonaqueous system.

The explanations given above demonstrate the wide scope and applicability of the present invention. Esterlike derivatives of N-methylol compounds which release acids such as citric, tartaric, adipic, lactic, glycolic, formic, and a-substituted acetic acids such as hydroxyacetic, methoxyacetic, cyanoacetic, chloroacetic and other similar acids are obvious examples of suitable derivatives to use as catalyst assist agents. Also, the ester-like derivatives may be formed from monoor polyfunctional N-methylolamides, such as carbamates, ureas, melamines, formamides, acetamides, hydrazides, pyrrolidones and similar amide-like compounds Further, the ester-like derivatives may be formed by partial acylation of the crosslinking agent used in the fabric treatment. Partial or total acylation of N,N- dimethylolamides to produce a group or range of acylated products provides a useful method for obtaining catalyst assist agents of varying solubility and reactivity. Of particular interest are N,N-bis(acyloxymethyl)amides which are expected, in general, to be relatively stable materials, but, once these agents are activated, i.e., acid is released, the product or monoacyloxymethylamide is expected to release acid at an accelerated rate. Thus, placing two acyloxymethyl groups on a single nitrogen atom of an amide provides another way to control the rate of acid released to the system.

The concentration of the crosslinking reactant in the pad bath can be varied depending on the particular textile processing conditions used, the type of textile being treated, and the properties desired'in the finished textile. It is generally preferred to use about 2 to percent by weight of the crosslinking reactant in the pad bath. A metal salt of a strong mineral acid is a suitable acidic catalyst to add to the treating solution of the process of the present invention. Magnesium chloride and zinc nitrate are examples of particularly suitable catalysts, and concentrations of about from 0.2 percent to 3 percent, by weight, of the acidic catalyst are generally preferred. The amount of the catalyst assist agent can be varied--depending upon the variables discussed above and concentrations of about from 0.1 .percent to 3 percent are generally preferred. Softeners and other additives may be used if desired. The wet impregnated textile may then be dried, preferably at a temperature of about from 60 to C. until it is dry to the touch.

Curing conditions can be varied widely as discussed above. Usually a dry impregnated fabric is heated at about from 100 to C for periods ranging from 15 to 0.5 minutes.

Following the curing operation it is preferablebut not necessary-t0 water-wash the treated textile to remove any unreacted materials. The washing operation can be carried out using the procedures and equipment conventionally employed for the washing of textiles. After it is washed and dried, the treated textile has the same appearance as the original untreated textile, and its feel is also essentially unchanged; but the treated fabric possesses resiliency, wrinkle resistance, and many other desirable properties.

The process of the instant invention'can be used to treat substantially any hydrophilic fibrous cellulosic material such as cotton, rayon, ramie, jute, and the like, which can be impregnated with a liquid and then cured.

The following examples are provided by way of illustration of how the invention can be reduced to practice, and these are in no way meant to indicate limitation of the invention. The detailed procedures given below in the examples are illustrative, and are not the only nor the specific conditions for the production of an acceptable finished textile. Modification of these procedures can be made, as will be apparent to those skilled in the art. In the examples all parts and percentages are by weight, unless noted otherwise.

The data in Table l demonstrate that the catalyst assist additives described in this invention, i.e., acetoxymethyl methyl carbamate and methoxymethyl acetate, are effective in increasing the rate of reaction of DMDHEU with cotton and are also effective in increasing the rate at which the resilience or wrinkle recovery of the fabric is developed by the treatment.

EXAMPLE 1 Four aqueous solutions of 98 parts were prepared such that on addition of two parts of one of the additives listed below, the final concentration of the pad bath was:

10 percent DMDHEU 4 percent MgCl,'6H,O 2 percent Additive The additives were as follows:

A. Water B. CH,OCH,O(CO)CH,

C. (CH ),CHOCH,O(CO)CH Because two parts of C was not soluble in 98 parts of the prepared solution, this .pad bath was discarded and was not used.

EXAMPLE 2 Fabric treatments: Samples of 80 X 80 cotton printcloth were dipped in the solutions of Example 1 and padded under identical conditions to give approximately the same wet add-on for each fabric padded,

i.e., four fabric samples were dipped into one of the three solutions in Example 1 to give a total of twelve fabric samples. The wet, impregnated fabrics were all dried 7 minutes at 60 C and then cured as shown in Table 1. All samples were washed in a warm alkaline water solution containing a nonionic detergent, and tumble dried. Selective testing was then performed on all 12 fabric samples and these data are also presented in Table l for comparative evaluation.

TABLE 1 Fabric Treatment Fabric Properties 1. A process for treating a substrate comprising cellulosic textile material, said process comprising applying an aqueous solution containing dimethyloldihydroxyethyleneurea, magnesium chloride, and N- acetoxymethyl methyl carbamate to said substrate, dry- 6 ing the thus-treated substrate, and subsequently curing the dried, treated substrate. A

- 2. A process for treating a substrate comprising cellulosic textile material, said process comprising applying an aqueous solution containing dimethyloldihydroxyethyleneurea, magnesium chloride, and methoxymethyl acetate to said substrate, drying the thus-treated substrate, and subsequently curing the dried, treated substrate. A

3. A process for imparting to a cellulosic fabric the quality of wrinkle resistance comprising a. impregnating the cellulosic fabric with an aqueous solution containing about from 2 to 20 percent by weight of dimethyloldihydroxyethyleneurea, about from 0.2 to 3 percent by weight of magnesium chloride, and about from 0.1 percent to 3 percent by weight of a catalyst assist agent selected from the group consisting of N-acetoxymethyl methyl carbamate and methoxymethyl acetate,

b. drying the wet impregnated fabric at about from 60 to C until the fabric is dry to the touch, and,

c. curing the dry impregnated fabric at about from 100 to C for about from 0.5 to 15.0 minutes.

4. The process according to claim 3, in which the catalyst assist agent is N-acetoxymethyl methyl carbamate.

5. The process according to claim 3, in which the catalyst assist agent is methoxymethyl acetate. 

2. A process for treating a substrate comprising cellulosic textile material, said process comprising applying an aqueous solution containing dimethyloldihydroxyethyleneurea, magnesium chloride, and methoxymethyl acetate to said substrate, drying the thus-treated substrate, and subsequently curing the dried, treated substrate.
 3. A process for imparting to a cellulosic fabric the quality of wrinkle resistance comprising a. impregnating the cellulosic fabric with an aqueous solution containing about from 2 to 20 percent by weight of dimethyloldihydroxyethyleneurea, about from 0.2 to 3 percent by weight of magnesium chloride, and about from 0.1 percent to 3 percent by weight of a catalyst assist agent selected from the group consisting of N-acetoxymethyl methyl carbamate and methoxymethyl acetate, b. drying the wet impregnated fabric at about from 60* to 100* C until the fabric is dry to the touch, and, c. curing the dry impregnated fabric at about from 100* to 180* C for about from 0.5 to 15.0 minutes.
 4. The process according to claim 3, in which the catalyst assist agent is N-acetoxymethyl methyl carbamate.
 5. The process according to claim 3, in which the catalyst assist agent is methoxymethyl acetate. 